Monodentate Acetate-Coordinated Electrolyte for Accelerated Zn2+ Desolvation and Stable Zinc Anodes

Abstract

Abstract Aqueous zinc-ion batteries (AZIBs) are promising candidates for large-scale energy storage, but their practical deployment is hindered by dendrite growth and water-induced side reactions. These challenges mainly arise from the high desolvation barrier of [Zn(H2O)6]2+, which slows interfacial kinetics and promotes irregular Zn deposition. Here, we propose a monodentate acetate-coordinated electrolyte (MACE) based on non-flammable trimethyl phosphate (TMP) as a co-solvent and KAc as a coordination regulator. Both theoretical and experimental analyses reveal that the acetate coordination mode critically governs Zn2+ desolvation behavior: compared with bidentate coordination, the monodentate configuration weakens the Ac–-Zn2+ interaction, lowers the desolvation energy barrier, and enables uniform, compact Zn deposition. Meanwhile, excess Ac– constructs a H-bonding network with water molecules, effectively suppressing water activity and related parasitic reactions. As a result, the MACE enables highly stable Zn anodes, delivering a Zn symmetric cell lifespan of over 4800 h at 0.5 mA cm–2 and 0.5 mAh cm–2. Moreover, Zn||NH4V4O10 full cells exhibit high capacity and excellent cycling stability. This work highlights the pivotal role of the anion coordination mode in Zn2+ desolvation and offers a new solvation-regulation strategy for advanced AZIBs.